; 正则序
(gcd 206 40)
  (gcd 40 (remainder 206 40))
    (gcb (remainder 206 40) (remainder 40 (remainder 206 40)))
      (gcb (remainder 40 (remainder 206 40)) (remainder (remainder 206 40) (remainder 40 (remainder 206 40))))

; 应用序
(gcb 206 40)
  (gcb 40 (remainder 206 40))
    (gcb 40 6)
